Who we "are" in adolescence does not foretell our adulthood. Because adolescence is a time of immense physiological, cognitive, and social change, teenagers confront daily challenges in navigating their shifting internal and external landscapes. These developmental shifts, and the resources needed to successfully pilot them, strain adolescents' capacity for adaptive and prosocial decision making in the context of risky or anti-social opportunities they confront (Centifanti, Modecki, MacLellan, & Gowling, 2014; Chein, Albert, O'Brien, Uckert, & Steinberg, 2011). As a result of these and other age-based demands, the risks for engaging in behaviors such as violence, sexual risk taking, substance use, school dropout, and other antisocial activities is higher during adolescence than any other developmental period (Bongers, Koot, Van Der Ende, & Verhulst, 2004). That said, maturation during adolescence around self-identity, cognitive abilities, and moral reasoning skills also provides a solid foundation for intervention during this time. In fact, neurological and psychosocial changes are tightly paired during adoles­cence, and this can set the stage for malleability in some. key factors that contribute to antisocial behavior, such as affective decision making, emotional valence, and sus­ceptibility to peer influence (Modecki, 2008; 2009; Monahan, Steinberg, Cauffman, & Mulvey, 2009). For this reason, prevention of adolescents' antisocial behaviors and set­tings, and programs that diminish their occurrence, are of sizable interest to researchers, policy makers, and practitioners. In this chapter, I briefly lay out theory and empirical research across major areas of psychology to help explicate the unique role of "adolescence" in the occurrence of risky and antisocial behaviors. I then tie our developmental understanding of adolescents' decision making and behavior to the legal arena, where considerations of teenagers' normative development should arguably impact their legal treatment. Finally, I briefly discuss policy and practice implications for adolescent antisocial behavior, broadly speaking, with a final note on areas for future research.